The Sun together with the group of celestial bodies that are held by its attraction and revolve around it.

An object that orbits a star, is large enough to be nearly spherical in shape, and has no other large object in its orbital path.

The path an object follows as it moves around another object.

An object in orbit around a larger object.

Objects in orbit move along an imaginary flat, disk-like surface.

A stretched-out circle.

The measure of how far an object’s orbit is from being circular.

An attractive force that exists between all objects that have mass.

A measure of how hard it is to stop a moving object.

The tendency for objects in motion to resist changes to their direction and speed (velocity).

The time it takes an object to travel once around the Sun.

The time it takes an object to complete one rotation.

The average distance from Earth to the Sun (about 150 million km).

The distance light travels in one year (about 9.5 trillion km).

The star in the center of our solar system around which the planets revolve and receive light.

A state of matter in which atoms have been stripped of some or all of their electrons, creating a mixture of free-moving positively charged ions and negatively charged electrons.

An object that orbits a star and is nearly spherical in shape but shares its orbital path with other objects of similar size but also aren't classified as satellites.

A natural satellite of a planet. Earth has one moon.

A meteoroid that has entered Earth’s atmosphere and produces a streak of light.

A small, rocky particle (from an asteroid) that moves through space made up of rock and metal.

A meteor that impacts the surface of a planet or a moon and creates an impact crater.

A small, rocky object that orbits the Sun.

A small, rocky, icy object that orbits the Sun.

A band of small celestial bodies beyond the orbit of Neptune (planet #8).

A spherical shell of celestial bodies believed to surround the Sun far beyond the orbits of the outermost planets.

The study of the origin, development, distribution, and future life in the universe.

The area around a star where it is not too hot and not too cold for liquid water to exist on the surface of the surrounding planets.

An organism that lives under extreme environmental conditions.

The natural process that occurs when certain gases in the atmosphere absorb and reradiate thermal energy from the Sun.

Referring to a class of chemical compounds in living organisms that are based on carbon (carbohydrates, lipids, proteins, and nucleic acids).

Any planet outside our solar system.